If you’re in a relationship, your sweetheart’s emotional state matters a lot to you. Of course, you care deeply about that person’s happiness. Also, due to a phenomenon called emotional contagion, you’re very likely to “catch” that person’s mood, and unfortunately, bad moods are more catching than good moods.

So how do you cope with a sweetheart or spouse who is irritable most of the time? Consider these factors:

1. Does your sweetheart seem exhausted and overwhelmed?

Maybe he or she isn’t getting enough sleep. Sleep is hugely important to mood and energy. If your sweetheart’s sleep is being interrupted or curtailed, figure out ways to help if you can. Turn out the light earlier, let your sweetheart sleep later at least some days of the week, work out a schedule so you two take turns getting a decent night’s sleep. Or if insomnia is the problem, help your sweetheart work on building good sleep habits: getting a little exercise, making the room very dark, spending the time before bed in a soothing activity, etc. (For more tips on getting good sleep, look here.)

2. Does your sweetheart nag a lot?

Just for a week or two, try to accommodate that nagging. If you’re being nagged to do a task that you plan to do, go ahead and do it at the first opportunity. Sure, maybe you’re right that it doesn’t have to be done today, but just do it today anyway. If you’re being nagged to do a task that you have no intention of doing, tell your sweetheart. Don’t keep procrastinating in hopes that the chore will be forgotten. That just leads to more nagging.

3. Is your sweetheart crabby about being nagged?

Try these strategies to stop yourself from nagging. (This is hard, but worth the effort.)

4. Does your sweetheart seem unable to make time for fun?

Try making some fun plans. Just saying, “Hey, let’s go to a movie,” isn’t sufficient. Pick an activity your sweetheart would enjoy, arrange for a babysitter if necessary, make reservations or buy tickets if necessary, take care of any tasks that need to be cleared out of the way before your sweetheart can relax. This issue may also be related to #2.

If your sweetheart seems unable to have fun on vacation, take a look at how he or she is spending the day. Reading on the beach—or chasing after little kids with a bottle of sunscreen? Rock climbing—or doing the same chores in a different locale? Try to arrange a vacation so everyone can have fun, according to their own idea of fun, at least some of the time.

6. Is your sweetheart crabby due to chronic pain?

Chronic pain, even if at a relatively low level, can really tax people’s moods. Encourage your sweetheart to take pain reliever, see a doctor, keep up with physical therapy, try acupuncture, start meditating, or whatever you think might work, and don’t just talk about it, take steps to help your sweetheart get help. Get recommendations, do research, make phone calls, pick up prescriptions, accompany your sweetheart to an appointment, give reminders, track symptoms—whatever is appropriate.

For some reason, people often don’t take steps to address discomfort. My husband, for instance, just doesn’t take pain reliever unless I go get it for him. So if he mentions having a headache or his bad knee is hurting, I go to the medicine cabinet.

When I’ve had chronic pain, I often denied it. I kept telling myself I was getting better, even when I wasn’t. Then, after I finally sought help, relief came fast. I endured several months of nagging eye pain that was cured by a quick trip to the eye doctor and a bottle of drops. I had excruciating back pain that was substantially relieved after I saw the physical therapist that my father-in-law had been recommending for months. Of course, sadly, chronic pain often doesn’t have an easy solution. But whatever the problem is, it’s worth trying to address it. Sometimes we need a little push to seek help.

7. Does your sweetheart’s crabbiness seem to go beyond the normal range of crabbiness?

Persistent low energy or insomnia, feeling paralyzed, difficulty concentrating, loss of appetite or overeating, persistent sad or empty feelings, feeling guilty or worthless, pains that don’t go away . . . these kinds of symptoms can indicate depression, and depression is very serious. Figure out a way to get help.

Now, as you look at this list, you might think, “Wait. My beloved, while not depressed, is quite irritable, and the irritable one is the one who should shape up. But these tips are things that I’m supposed to do.” True! The fact is, as the Sixth Splendid Truth holds, the only person you can change is yourself. But if you change—a relationship changes—and if you behave differently, you may find your sweetheart’s crabbiness lifting.

What am I missing? Have you found other good ways to cope with this issue? I myself am very easily irritated, and it’s tough on my family, so I spend a lot of time thinking about it.

Gretchen Rubin is the author of the #1 New York Times Bestseller, The Happiness Project—an account of the year she spent test-driving the wisdom of the ages, current scientific studies, and lessons from popular culture about how to be happier. On her popular blog, The Happiness Project, she reports on her daily adventures in the pursuit of happiness. Gretchen is also on Facebook and Twitter.

* The Happiness Project has been on the New York Times paperback bestseller list for one year. Yep! One solid year. Order your copy.